Dormers in Auderghem

What does this work involve

A dormer is a structure that projects out of the roof slope to create a vertical opening. It brings light into the attic, improves headroom in a mansard space, and sometimes creates access to a small balcony or terrace.

Several types exist: the classic dormer with a straight front and its own little roof (the model you see on many townhouses in Auderghem), recessed dormers that follow the roof pitch, gabled dormers (two symmetrical slopes), and zinc dormers that integrate into contemporary roofs.

We handle three kinds of situations: creating a dormer (modifying the structure, creating the opening, fitting the structure and the waterproof junctions); renovating an existing dormer that leaks or whose waterproofing is failing; and complete replacement when the dormer is too degraded or you want to change the style.

When should you act

A few concrete situations:

• Damp patches appear on the interior wall under the dormer or on the adjacent ceiling
• The timber of the dormer frame is swollen, cracked or shows traces of rot
• The zinc or lead junction around the dormer is lifting or cracking
• You want to convert your attic and the existing dormer is too small or in poor condition

Why it happens

Dormers are natural weak points in a roof because they create complex angles and junctions. Water seeks out those angles. The zinc cladding the cheeks and base of a dormer works hard through the hot-cold cycles, and eventually cracks or comes loose at the solders.

On the houses of Auderghem built between 1920 and 1960 (the villas and townhouses of Boulevard du Souverain and its surroundings), the original dormers are often 60, 70 years old. Their timber structure may still be good, but the lead or zinc junctions have rarely survived without problems. A regular inspection costs little; waiting for a leak to settle into the structure costs much more.

What makes the price vary

For a new dormer, the price mainly depends on the size of the opening, the type of dormer chosen, and the structural modifications required. A dormer that requires cutting one or two rafters takes more work than an opening in a clear space.

For a renovation or replacement, the state of the surrounding structure is decisive. If the wood has taken on moisture over several years, we can't simply redo the zinc junction without treating the wood first. The junction material counts too: zinc is more durable but more expensive than galvanised steel. For townhouses, zinc often imposes itself for architectural consistency.

Repair or rebuild

A timber dormer with light traces of moisture can often be saved: treating the wood, replacing the damaged elements, a new waterproof junction. But if the structure is too degraded, attempting a partial repair sometimes costs as much as a complete rebuild — and is less reliable.

We tell you clearly what we see and what we recommend. No need to redo everything if a repair holds up. But if it won't hold, better to know before paying twice.